冻结速率对血小板冷冻干燥保存的影响

冷冻干燥法是使血小板能够长期保存的一种理想方法。冻结过程对血小板的冻干保存至关重要。采用梯度降温、搁板预冷、液氮冻结等三种冻结方式,研究了冻结速率对血小板冷冻干燥保存恢复率的影响。实验结果表明用搁板预冷的方式冻结并干燥的血小板复水后的恢复率最高,达到(93.0.2)%,此时的冻结速度约为10℃/min。扫描电镜照片显示冻干复水后的血小板保持了完整的细胞结构,但与新鲜血小板相比略呈球形。冻干复水后的血小板对1U/ml凝血酶的最大聚集率接近于新鲜血小板,但聚集速度比新鲜血小板慢。     

线粒体形态学改变与细胞凋亡

近年来,对于线粒体形态学以及其在凋亡过程中的改变和作用的研究打破了传统的观点。正常情况下,线粒体在细胞内相互连接成管网状结构,并发生着频繁的融合与分裂。融合和分裂由一系列蛋白质介导,二者之间的动态平衡维持着线粒体的形态和功能。在细胞凋亡的早期,线粒体融合和分裂失平衡,导致线粒体管网状结构碎裂和嵴的重构,这些改变对线粒体随后的变化以及凋亡的发生具有重要的意义。融合和分裂的蛋白质不仅调控线粒体形态和细胞凋亡过程,也和某些凋亡相关疾病有关。此外,促凋亡的Bcl-2蛋白可能通过改变线粒体的构形来调控凋亡过程。     

Efficient transient expression of human GM-CSF protein in Nicotiana benthamiana using potato virus X vector

The human granulocyte macrophage colony-stimulating factor (GM-CSF) is a glycoprotein with important clinical applications for the treatment of neutropenia and aplastic anemia and reducing infections associated with bone marrow transplants. We evaluated the potential for using a potato virus X (PVX) viral vector system for efficient expression of the biologically functional GM-CSF protein in Nicotiana benthamiana leaves. The GM-CSF gene was cloned into PVX viral expression vector, driven with the CaMV 35S promoter. Gene transfer was accomplished by inoculating N. benthamiana leaves with the plasmid DNA of PVX vector containing the GM-CSF gene. The expression level of the recombinant GM-CSF protein was determined with ELISA and its size was confirmed by Western blot analysis. The results showed that: (1) leaf age significantly affects GM-CSF protein concentration with younger leaves accumulating 19.8 mg g⁻¹ soluble protein which is 2.6 times the concentration in older leaves, (2) recombinant protein accumulation within a given leaf declined slightly over time but was not significantly different between 7 and 11 days post-inoculation (dpi), and (3) the two leaves immediately above the inoculated leaves play an important role for GM-CSF accumulation in the younger leaves. Protein extracts of infected N. benthamiana leaves contained recombinant human GM-CSF protein in concentrations of up to 2% of total soluble protein, but only when the pair of leaves immediately above the inoculated leaves remained intact. The recombinant protein actively stimulated the growth of human TF-1 cells suggesting that the recombinant human GM-CSF expressed via PVX viral vector was biologically active.     

黄芪属一新改级

作者通过对药用黄芪野生资源的调查, 结合查阅大量标本及考证模式标本, 发现淡紫花黄芪Astrasalus membranaceus(Fisch. exLink)Bge. var. membranaceus f. purpurinus(Y. C. Ho)Y. C. Ho不仅花旗瓣顶端为紫红色;而且花小;小叶小, 质地厚, 小叶对数少;果小且果皮厚;限分布于我国西南地区。认为作为亚种处理比较合适。即A. membranaceus(Fisch. exLink)Bge. subsp. pallidipurpureus(Hsiao)X. Y. ZhuetC. J. Chen.     

Proposed GSSP for the base of Cambrian Stage 7, coinciding with the first appearance of Lejopyge laevigata, Hunan, China

The Luoyixi section, exposed in a roadcut along the Youshui River (Fengtan Reservoir), Guzhang County, Hunan Province, China, is proposed as the stratotype for the base of an unnamed stage boundary (base of the Cambrian stage provisionally termed Stage 7). The proposed position of the GSSP is 121.3 m above the base of the Huaqiao Formation, at a horizon coinciding with the first appearance of the cosmopolitan agnostoid trilobite Lejopyge laevigata. The section fulfills all the requirements for a GSSP, and the horizon can be constrained not only with the primary stratigraphic marker (L. laevigata) but also with secondary biostratigraphic, sequence-stratigraphic, and chemostratigraphic correlation tools. The first appearance of L. laevigata is one of the most readily recognizable levels in the Cambrian, and can be correlated with precision to all paleocontinents.     

Mdm1/Snx13 is a novel ER–endolysosomal interorganelle tethering protein

Although endolysosomal trafficking is well defined, how it is regulated and coordinates with cellular metabolism is unclear. To identify genes governing endolysosomal dynamics, we conducted a global fluorescence-based screen to reveal endomembrane effector genes. Screening implicated Phox (PX) domain–containing protein Mdm1 in endomembrane dynamics. Surprisingly, we demonstrate that Mdm1 is a novel interorganelle tethering protein that localizes to endoplasmic reticulum (ER)–vacuole/lysosome membrane contact sites (MCSs). We show that Mdm1 is ER anchored and contacts the vacuole surface in trans via its lipid-binding PX domain. Strikingly, overexpression of Mdm1 induced ER–vacuole hypertethering, underscoring its role as an interorganelle tether. We also show that Mdm1 and its paralogue Ydr179w-a (named Nvj3 in this study) localize to ER–vacuole MCSs independently of established tether Nvj1. Finally, we find that Mdm1 truncations analogous to neurological disease–associated SNX14 alleles fail to tether the ER and vacuole and perturb sphingolipid metabolism. Our work suggests that human Mdm1 homologues may play previously unappreciated roles in interorganelle communication and lipid metabolism.     

PFTK1 Promotes Gastric Cancer Progression by Regulating Proliferation,Migration and Invasion

PFTK1, also known as PFTAIRE1, CDK14, is a novel member of Cdc2-related serine/threonine protein kinases. Recent studies show that PFTK1 is highly expressed in several malignant tumors such as hepatocellular carcinoma, esophageal cancer, breast cancer, and involved in regulation of cell cycle, tumors proliferation, migration, and invasion that further influence the prognosis of tumors. However, the expression and physiological significance of PFTK1 in gastric cancer remain unclear. In this study, we analyzed the expression and clinical significance of PFTK1 by Western blot in 8 paired fresh gastric cancer tissues, nontumorous gastric mucosal tissues and immunohistochemistry on 161 paraffinembedded slices. High PFTK1 expression was correlated with the tumor grade, lymph node invasion as well as Ki-67. Through Cell Counting Kit (CCK)-8 assay, flow cytometry, colony formation, wound healing and transwell assays, the vitro studies demonstrated that PFTK1 overexpression promoted proliferation, migration and invasion of gastric cancer cells, while PFTK1 knockdown led to the opposite results. Our findings for the first time supported that PFTK1 might play an important role in the regulation of gastric cancer proliferation, migration and would provide a novel promising therapeutic strategy against human gastric cancer.     

High genetic differentiation and low genetic diversity in Incarvillea younghusbandii, an endemic plant of Qinghai-Tibetan Plateau,revealed by AFLP markers

Incarvillea younghusbandii Sprague (Bignoniaceae) is a perennial herbaceous plant endemic to Qinghai-Tibetan Plateau. As a species of medical and horticulture importance, I. younghusbandii is threatened by over exploitation and habitat fragmentation. In this study, we analyze the genetic diversity and population structure of I. younghusbandii using amplified fragment length polymorphism (AFLP) markers. Our data reveal very low levels of genetic diversity in seven natural populations across Tibet. Specifically, at population level, the average Nei's genetic diversity index (H_E) and Shannon's diversity index (I) were 0.063 and 0.096, respectively. In contrast, high genetic differentiation among populations (Gst = 0.6238, Φ_ST = 0.614) is detected. The results of Neighbor-joining cluster, PCO, and STRUCTURE assignment reveal consistent pattern, suggesting seven well-defined genetic groups that are concordant with their geographical origins. The possible mechanisms and implications of these findings for conservation are discussed.